Gardening irrigation systems are known, which comprise so-called “pop-up” water dispensing devices, consisting of a main tubular outer body, vertically buried underground, and of an inner body or moving piston slidably inserted into said main body and ending with a water dispensing head provided with a diffusing unit. The piston is typically elastically held in a resting position with its head lowered, and it is displaceable to an irrigation position with head lifted by the pressure of the water supplied at the base of the main body by a suitable water supply system.
Dispensing devices for such underground irrigation systems are described, for example, in patents EP 1 043 075 A1 and EP 1 173 286 B1.
In order to allow the dispensed water jet to be adjusted, an adjusting screw is usually included between the dispensing head and the moving piston, which can be accessed only once the terminal ferrule of the main body has been disassembled and the head has been separated from the piston. An Allen wrench inserted into an underlying cavity of the adjusting screw is used to change the position of the screw, thereby adjusting the flow rate of the water dispensed.
This operation is clearly quite complex and often requires the intervention of skilled personnel.
U.S. Pat. No. 3,088,677 A describes a dispensing head for a pop-up underground sprinkler comprising a jet adjusting unit which can be externally accessed when the head is lifted to the irrigation position.
In light of this prior art, it is the object of the present invention to provide a dispensing head for pop-up underground sprinkler which has a new flow adjusting system which is easy to be accessed and operated.